Influence of spiky twisted tape insert on thermal fluid performances of tubular air–water bubbly flow

Chang, Shyy Woei; Lees, Arthur W.; Chang, Hsien Tsung

doi:10.1016/j.ijthermalsci.2009.05.002

Cited by 25 publications

(6 citation statements)

References 30 publications

(71 reference statements)

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“…They concluded that the thermal coefficient efficiency was influenced by the clearance ratio of the twisting plate while a clearance ratio of zero offers the best thermal performance. Chang et al 15 discussed the pressure drop and heat transfer of water–air fluid running in a plain tube and another tube with a spiky TT inside. Their results showed that the scattered air bubbles forming in the plain tube were mixed by the TTs, significantly improving the pressure drop and heat transfer compared to the case of the single‐phase fluid.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

et al. 2021

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In the present study, two various passive methods for heat transfer enhancement, including conical ring and wire coil are placed in a tube as turbulators. Four conical rings with four side holes are utilized with the same distance. The wire coil is employed at the center of the tube. The considered Reynolds numbers are between 4000 and 10,000. The studied geometrical parameters contain the pitch and diameter of a wire coil. Four different pitches of wire coil, including 10, 12, 14, and 16 mm, are evaluated. Furthermore, four values of wire coil diameter such as 2, 4, 6, and 8 mm are certain. The obtained numerical results displayed that by declining the pitch of a wire coil (37.5%), the average Nusselt number increases by about 143%. Also, augmentation in wire coil diameter by 300% leads to a growth in average Nusselt number by about 131%. Moreover, owing to utilizing two various turbulators, the pressure drop is significantly high in comparison with the bare tube. At Re = 10,000, growth in the inner diameter of the wire coil by 300% leads to an increase in thermal performance by about 36.12%. Moreover, as the pitch of the wire coil rises by 60%, the thermal performance declines by about 35.71%.

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Section: Introductionmentioning

confidence: 99%

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

et al. 2021

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“…Heat transfer enhancement is very important to modern industrial process such as heat exchangers and refrigeration systems. Researchers put forward lots of techniques [1,2] to improve heat transfer efficiency, which include vortex generator (VG). Planar or solid VG [3,4] are frequently applied due to its simple form and low cost.…”

Section: Introductionmentioning

confidence: 99%

Enhanced heat transfer under the influence of coherent structure induced by arc vortex generator in square pipe flows

et al. 2019

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Experiments and numerical simulations were both performed to investigate coherent structures and heat transfer process in a square pipe turbulent flows induced by arc vortex generator. The velocity fields of induced turbulent flow was obtained by planar particle image velocimetry. The analysis of velocity profiles revealed the co-existence of various coherent structures. Turbulent fluctuation quantities, such as turbulent intensities, Reynolds stress, etc. exhibited the different behaviors of fluid motions introduced by arc vortex generator. Probability density function of swirling strength showed the complication of the vortex-rotating. Heat transfer process was simulated using large eddy simulation. The results of Nusselt number achieved the maximal improvement 57% with the use of arc vortex generator. The distribution of Nusselt number was in good agreement with the distribution of coherent structures, especially hairpin vortices and subsequent secondary coherent structures, which highlighted the influence of coherent structures by arc vortex generator on heat transfer enhancement.

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“…Passive VG are more commonly used since they are characterized by their efficiency, economy, manufacturing simplicity and maintenance ease, opposite to active VG which are energy consumers and less easy to implement. These VG have various types which include helical and twisted inserts [7,8], dimples or protrusions [9,10], cylindrical tubes [11e14], transverse vortex generators (TVG) [10,15,16], longitudinal vortex generators (LVG) [17e23], plane or curved surface of VG [24,25] or a combination of the above types [10,22,26e29].…”

Section: Introductionmentioning

confidence: 99%

Novel design of delta winglet pair vortex generator for heat transfer enhancement

Oneissi

Habchi

Russeil

et al. 2016

International Journal of Thermal Sciences

103

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Heat transfer is a naturally occurring phenomenon that can be greatly enhanced with the aid of vortex generators (VG). Three-dimensional numerical simulations of longitudinal vortex generators are performed to analyze heat transfer enhancement in parallel plate-fin heat exchanger. The shear-stress transport (SST) k-u model is adopted to model the flow turbulence. Empirical correlations from the open literature are used to validate empty channel simulations. First, numerical simulations are conducted for the classical delta winglet pair (DWP) which is introduced as the reference case in this study. Then, an innovative VG configuration, named inclined projected winglet pair (IPWP), is examined and it shows superior performance relative to the DWP. The IPWP exhibits similar heat transfer rates than that of the DWP but with lower pressure drop penalty due to its special aerodynamic design. The local performance is analyzed based on the streamwise distribution of Nusselt number and friction coefficient criteria in addition to vorticity. This study highlights the different mechanisms involved in the convective heat transfer intensification by generating more vortices using more aerodynamic VG shape while decreasing the pressure drop penalty.

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Influence of spiky twisted tape insert on thermal fluid performances of tubular air–water bubbly flow

Cited by 25 publications

References 30 publications

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

Heat transfer improvement in a tube by inserting perforated conical ring and wire coil as turbulators

Enhanced heat transfer under the influence of coherent structure induced by arc vortex generator in square pipe flows

Novel design of delta winglet pair vortex generator for heat transfer enhancement

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